Apparatus for imposing vibrato on sound



D. J. LESLIE 2;6Z2,693

APPARATUS FOR IMPOSING VIBRATOI on souun Original Filed July 9, 1945Don/41.0 z'Z LESLIE,

INVENTOR.

BY f

flrroe/ve'yi Dec. 23, 1952 Patented Dec. 23, 1952 UNITED STATES PATENTFF I CE APPARATUS FOR IMPOSING VIBRATO SOU 7 Claims. 1

The present invention relates to the production of musical tones, andmore particularly to the production of tones possessing pitch tremolo orvibrato.

This application is a division of my application for Acoustic Apparatus,filed July 9, 1945, Serial No. 603,850, now Patent No. 2,489,653, whichis a continuation-in-part of my application for Acoustic Apparatus,filed December 10, 1940, Serial No. 369,413, now abandoned.

In playing an ordinary musical instrument, as a stringed or windinstrument, or in singing, the pleasing quality of the music may beenhanced by producing a pitch tremolo or vibrato. This vibrato effect inthe case of an instrument is produced by a slight, rapid motion of thefinger on the appropriate key or string, causing cyclic and rapid minorvariations of pitch.

As described in the above applications, a tremolo effect can be producedby moving a sound transmitting channel at a certain rate, of'the orderof between five and eight cycles per second. The sound transmittingchannel may be associated with a loud speaker, the rotation of thechannel causing its mouth to move alternately toward and away from thelistener at a frequency corresponding to the vibrato. In this manner,the pitch of the sound issuing from the speaker and heard by thelistener is alternately increased and decreased.

In connection with a rotating sound channel, such as a horncommunicating with a speaker, horns of comparatively small dimensionsare usually employed for medium and high frequencies. The higher soundfrequencies emitted from such horns have strong directionalcharacteristics, and are not widely distributed. The medium frequenciesare more widely distributed, but also have marked directionalcharacteristics.

Accordingly, it is an object of the present invention to provideanarrangement for altering the character of the vibrato issuing from ahorn or similar sound channel.

Another object of the invention is to provide a horn apparatus in whichthe higher and medium frequencies issuing from the horn are more widelydistributed. 7

Still another object of the invention is to provide a sound apparatusembodying a horn in which the directional characteristics affecting thevibrato can be varied.

This invention possesses many other advantages, and has other objectswhich may be made more clearlyapparent from a consideration of severalforms in which it may be embodied. Such forms are shown in the drawingsaccompanying and forming part of the present specification. These formswill now be described in detail,,illustrating the general principles ofthe invention; but it is to be understood that such detailed descriptionis not to be taken in a limiting sense, since the scope of the inventionis best defined by the appended claims.

Referring to the drawings:

Figure 1 is a side elevation of an apparatus embodying the invention;

Fig. 2 is a fragmentary section on an enlarged scale, taken along theline 2-2 on Fig. 1;

Fig. 3 is a view similar to Fig. 2, showing another embodiment of theinvention;

Figs. 4, 5 and 6 are diagrams of radiation patterns useful in explainingcertain aspects of the invention; I

Fig. 7 is a fragmentary view, similar to Fig. 2, of another embodimentofthe invention.

As disclosed in Fig. l, a directional sound horn I6 is adapted totransmit sound from a stationary speaker H, or similar source, withwhich it is in sound communication. The horn is of generally elbowshape, with its outlet opening l2 disposed eccentrically or to one sideof the axis l3 about which the horn is to be rotatable. Rotation of thehorn is accomplished by securing a pulley [4 to its inner hub end I 5, abelt [6 passing around this pulley and also around a driving pulley llsecured to the shaft [8 of an electric motor [9.

The horn I0 is rotated at a speed capable of imparting the desiredvibrato to the sound emit-' ting from its mouth I2 (which, as indicatedabove, is of the order of five to eight cycles or revolutions persecond). Where the frequencies supplied by the speaker H are in themedium and high ranges, the horns ordinarily are of rather smalldimensions. Such horns have a radiation pattern of the form indicated bythe broken lines in Fig. 4. The sound emitted will have a peak amplitudedirectly in front of the horn, the higher frequencies having strong di-'rectional characteristics, as indicated by the curve marked A, and themedium frequencies being more widely distributed, as indicated by thecurve marked B.

By providing a deflector comprising a pair of plates 20, 2| oppositelyinclined across the mouth l2 of the horn in the plane of rotation of thehorn, the radiation pattern may be changed to have a form such as thatindicated by the curve C in Fig. 5. In that figure, it will be notedthat the peak amplitude in front of the horn has been substantiallyreduced and the sound distributed over a wider area. Furthermore, thedirectional properties of the higher frequencies have been decreased sothat these and the medium frequencies have about the same distribution.Such a deflector arrangement also affects the vibrato by increasing theapparent length of the horn which increases the Doppler effect.

As shown most clearly in Fig. 2, the plates 20, ,2] are large withrespect to the mouth [2 of the horn I9, and are disposed at right angleswith respect to each other. Various radiation patterns may be providedby utilizing larger or smaller plates, or a difierent inclination, orboth. Thus, in Fig. 3, several pairs of smaller plates 22, 23, moresteeply inclined, are shown as provided across the mouth [2 of the horn.The radiation pattern for a horn with such a deflector may be of thetype indicated in Fig. 6,. and is generally intermediate the curves Aand B of Fig. 4 and the curve C of Fig. 5. The amplitude peak directlyin front of the horn is not very pronounced, and the sound is quitebroadly distributed, the medium frequencies (curve D) being somewhatmore widely distributed than thehigher frequencies (curve E).

The directional characteristics of a horn in the plane of rotationstrongly affect the vibrato, while the same characteristics in a planenormal thereto have no effects. Accordingly, if .a horn with differentdirectional effects in the two planes is arranged so that itsdirectivity is effective in either its plane of rotation or at ninetydegrees thereto, completely different effects can be obtained. Othereffects can also be obtained by directing the horn at an intermediateposition. To permit adjustment of the mouth 12 and plates 20, 2|, or 22,23 of the horn, the horn is formed of two sections, namely, an innersection and an outer section 24. One of these sections, as the outersection 24, has a collar secured to it which can be attached to theinner section I5 by means of a set screw 26. Tightening of the set screwagainst the inner section serves to couple the two sections I5, 24together.

By loosening the set screw 25, the outer section 24, which has differentdirectional properties in different planes, by virtue of the directivityplates and 21, or 22 and 23, may be angularly adjusted upon the innersection I5 to vary the vibrato; whereupon, the set screw 25 is againtightened.

Itmay be desirableto provide a deflector which will produce the sameradiation pattern in all planes. horn I 0 may be provided having aconical deflector 21 suitably supported at its mouth portion l-2.Obviously, the proportions of the conical deflector 2'! may be varied toproduce different characters of vibrato.

The inventor claims:

1. In apparatus for imposing vibrato on mu sical sound, a source of saidsound. means form ing a sound channel for directing the sound from saidsource and having a sound emitting opening, means mounting said soundchannel for rotation about an axis spaced from the opening, a conefacing said opening to alter the radiating properties of said channel,and means for continuously rotating said sound channel about said axis.

2. In. apparatus for imposing vibrato on musical sound, a source of saidsound, means forming a sound channel for directing the sound from saidsource and having a sound emitting opening, means mounting said soundchannel for rotation about an axis spaced from the opening, and a pairof oppositely inclined plates extending across said opening to broadenthe radiating properties of said channel in planes normal to said axisof rotation, and means for continuously rotating said sound channelabout said ax1s.

3. In apparatus for imposing vibrato on musical sound, a source of saidsound, a horn for For this purpose, as shown in Fig. 7, a

Number directing the sound from said source and having a sound emittingopening, means for continuously rotating said horn about an. axis spacedfrom the opening, and means providing one or more inclined surfacesextending across said opening to broaden the radiating properties ofsaid horn in planes normal to said axis of rotation.

4'. In apparatus for imposing vibrato on musical sound, a source of saidsound, means forming a sound channel for directing the sound from saidsource and having a sound emitting opening, means mounting said soundchannel for rotation about an axis spaced from the opening, a pluralityof pairs of oppositely inclined plates extending across said opening tobroaden the/radiating properties of said sound emitting opening inplanes normal to said axis of, rotatiomand. means for continuouslyrotating said sound channel about said axis.

5. In, apparatus for imposing vibrato: unsound. asource of said sound, ahorn for directing the sound from said source, said horn having an innerportion communicable with said source and an outer portion providedwitha sound emitting opening, means adjustably securing said inner and outerportions together to enable said outer portion to be shifted angularlywith respect to said inner portion, means for rotating said horn aboutan axis spaced from the opening, and means forming a deflectorcooperating with said opening to vary the directive properties of saidhorn in different planes.

6. In apparatus for imposing vibrato onsound: a source of sound; meansforming a sound channel for directing the sound from said source andhaving a sound emitting opening; means for continuously rotating saidsound forming channel at a rate of from five to, eight, revolutions permin,- ute, about an axis spaced from the sound emits ting opening; and adeflector cooperating with the opening and having a deflecting surfacethat is transverse to the direction of motion or the surface.

7. In apparatus for imposing vibrato on sound: a source of sound; meansforming a sound channel for directing the sound from said source, saidmeans including walls defining a sound emitting. opening that providesbroadened directive properties in one direction transverse to saidchannel; means mounting said channel forming means for rotation about anaxis spaced from theopening; and means for continuously rotating saidchannel forming means about, said axis; said mounting means being soarranged. and constructed that said one direction substantiallycoincides with the instantaneous direction of rotation of said openingabout said axis.

DONALD J. LESLIE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date 647,147 Myers Apr. 10, 190.0 1,174,358Sexton Mar. '7, 1916 1,184,938 Fischer May 30, 1916 1,240,050 JohnsonSept. 11, 1917 1,759,556 Hutchison May 20, 1930 2,287,105 KannenbergJune 23, 1942 FOREIGN PATENTS Number Country Date 404,937 Great BritainJan. 15,1934

